As someone with self-diagnosed mild depression and probably adhd, I've struggled with this.

Lots of people have suggested running or walking, can confirm, that does help. I would also add music to that. Throw on headphones, start your favorite playlist, crank it up good and loud, and go for a walk/jog/run. No one is watching you, no one is judging you. Silently lip sync sing with the songs as expressively awesome as you can (or sing out loud for real if you can, but I know this would be hard for me, for whatever reason I'm much less self conscious about my ridiculous facial gymnastics as long as I'm quiet about it). Like for real, pretend this is your song, and you're performing it live at your band's concert. Entertain the shit out of your imaginary audience. Belt it out like there's no tomorrow. To quote Straylight Run's "Existentialism on Prom Night," sing like you think no one's listening. Combined with the physical activity, you'll feel great when you get back home. For even better effect, find a bunch of songs where the tempo matches your walking speed. Then you can really get into a groove with it.

I also go on walks with my wife most evenings now, no music/headphones, just kinda small talk and enjoying each other's company, and it's helped get some things back on track with our marriage too. Better communication. Not both of us sitting on the couch silently doomscrolling and ignoring each other.

I can also suggest 3d printing as another good hobby, though this one will cost you, so it comes with the caveat that you'll probably want to have at least a bit of discretionary income if you want to pick this one up. There are tons of free, ready-made models on sites like thingiverse.com, thangs.com, or printables.com. Public libraries sometimes have 3d printers available for public use, and any makerspace worth their salt will have some too, if you're in an area that has something like that. So you can piddle around with it a bit before you really start laying out cash, see if it's something you'll like.

Start small, find a dinky little trinket or toy or something that can be printed quickly, and watch that mfer come into existence layer by layer. It's addicting. When the print bed slides out at the end with a physical object that didn't exist an hour ago, it's kind of fantastic.

Once you decide that you like it, you'll want to get a printer of your very own. You can find very hands-on tinkery printers (creality ender 3 series) for $100 and up, if you're good getting your hands dirty and buying more parts to "fix" some of the entry-level shortcomings. Good, ready-made "as good as your gonna get" options from Prusa or Bambu are higher priced initially ($500+) but won't require nearly as much extra money for upgrades and tweaks. Filament usually costs about $20-30/roll depending on how fancy you want. You can do toys. You can do lithophanes (cool 3d printed photographs). You can print replacement parts for random shit in your house that breaks. Guns. Action figures. You can print an entire fucking life sized Tyrannosaurus Rex skeleton (Reddit link, warning to anyone who's avoiding the old site). And all the while, you'll need to read and research and tweak and change and do all kinds of little mental tasks to engage yourself and pull out of your funk.

Your thing will fail sometimes. You'll run out of filament. Your settings will be wrong. You'll end up with a big blob of plastic spaghetti. But that gives you incentive to find and fix what went wrong and try again. It'll come out right eventually, and it feels great when it does.

Once you've gotten your feet wet with models from the Internet, you can get into starting to learn modeling yourself, with Blender or FreeCAD or any number of other apps. And if you thought it felt good when your cheesy little boat or octopus from the Internet finished, let me tell you... When your own model, that you created from absolutely nothing, comes off the printer as a real honest-to-god physical object, looking exactly like it did in your head, it's sublime!

Anyway. Good luck to you. Good on you for reaching out and looking for ways to improve yourself. I hope you find something that works for you.

I was in a similar situation an year ago. I'm still not where I want to be, but I'm getting there.

Ideally, a routine which incorporates enough physical exercise, challenge and rest will get you to a much better state of mind.

There's a reason why many of the comments on this post are about physical activities. It just works.

exercise

Some form of exercise, I like weight lifting (bodyweight fitness is also fantastic)

Be disciplined and go even when you don't want to because when you're there you're glad you are. If you progressively overload every workout you aim for a new best, something to strive for. Then at the end you get the happy chemicals. Working out is amazing for improving mental health, and you get good visual and physical health benefits too.

Photography - added benefit is that you will usually go out for this

Music - an instrument is good

Drawing/Painting

Programming (hit or miss, I found learning unity was fun)

Video making - recording video games playthroughs, cooking, and so on.

Finally, one that usually everyone probably also may mention - Therapy - not a hobby but having to be able to talk about it is often good

This is of course not an exhaustive list - but it depends on what your interests are. Hope this is a good pointer to what you're looking for.

Could try 3D printing. I recently picked up an Ender 3 printer and have been having a lot of fun. I'm in a pretty good spot with a few figures printed and I'm ready to start doing the clean up and polishing type stuff. After I feel like I have a good process I'll start figuring out the best ways to paint.

It's been a fun hobby with a seemingly endless amount of depth, so there's always something to learn or just improve your current process.

The printer I got, plus the filament was around $195 to get started. Budget permitting I think its a fun creative outlet.

Try writing anything. It doesn't matter what. It doesn't matter how much. Just try. Whenever you have the impulse, just write something. Don't worry about what it is, just let it out. Do it for as long as you like: 30 seconds or 30 minutes.

You never have to show any of it to anyone... until you suddenly decide one day that you'd like to. Until then, it's just for you.

Peace.

Singing. It literally bumps up your dopamine level.

It may have been suggested but a friend of mine who suffers with depression really enjoys jigsaws and lego?

Hiking, biking, walking, and jogging are all solid options.

Exercise is a definite one. This is actually coming from a medical side, not just a personal one. There's a lot of data there.

However I think hobbies that are 'measurable' are also really good. Ones where you can feel like you accomplished something. So things like painting, drawing, learning something, reading, where you can feel like youve finished something I feel really helps.

So a good idea might be combining the two. Maybe an exercise with a goal in mind. Or maybe take a few karate classes, with the goal of working towards your first belt. Or biking a certain distance every day to reach a total amount for a month. I personally find when i can see that my hobby has some measurable accomplishment, I personally feel more satisfied with that

Also for me social things help a lot. Im a very social person, but can get such in a rut. Finding more ways to be social can help expand and open you up to other things

Gaming! There's so many amazing games out there in all sorts of genres.

Pick up whittling. This what I did when I was struggling in early covid. The start up cost is low and u can get as creative as u want. Im not very creative so make spoons and give them to family and friends but also make little figures like gnomes, wizards, rabbits, fish.

If u got wood and a semi decent knife, u can start right now

If you live somewhere rural...birdwatching.

I recently started watching videos of people mowing lawns and it's been making me feel great.

Echoing others, outdoor exercise is definitely the most restorative activity for me.

To add to this though, I also have taken up Photography as a way to add to or enhance my hobbies and activities.

I usually bring a camera with me on hikes, trips, walks, bike rides, nearly anytime I leave the house. It helps me see the world with my creative switch “on” but without the pressure of having to take an amazing photo - something I feel when I only bring out a camera for special occasions.

I also want to stress the importance of taking photos for yourself as the primary goal, and if only sharing photos that you personally like, not photos that you think others will like.

Exercise is what helped me. I tried kayaking, found it to be nice but a lot of overhead. So cycling became a passion. Cover a lot of ground, see nature, get a lot of perspective, release endorphins in a healthy way. I did both road cycling and mountain biking.

It basically saved me from some dark times. I have a young child now, so on a hiatus, but will be back to it once she is old enough to go on rides.

If you are lacking motivation, find something where you can start small, or work on in your bedroom. Make it as easy as possible to work on your hobby. Some examples include gaming (switch or laptop right next to the bed), or maille (start small with bracelets and move up to bags and belts before doing anything big).

As I don't see it already mentioned - needle felting. It's really fun, simple to learn yet hard to master and can be a great creative outlet. I'm still a beginner myself, but have already managed to make some okay looking things, and as you get better the things you make can be great small gifts for friends and family.

I believe there are some fairly inexpensive beginner's kits you could get that contain everything to get you started, and youtube has some really nice tutorials. There are also several ebooks with needle felting ideas and templates. What I like to do, to not feel too bad when my thing looks nothing like the thing in the picture, is to look up a tutorial to get a basic idea and then amend according to my ability and colors I have available.

In any case and whatever you end up actually doing, I really hope you find something you enjoy.

D&D and tabletop gaming in general has helped a lot with my social anxiety and mental health.

A really simple creative hobby could be drawing mandalas.
You can completely freehand it, or use a circle tool like a compass to make guides to make it more symmetrical. Search for "mandala shapes" if you want some ideas for basic shapes to use.

As Heliumfart said, music works well. Even if you're not musically inclined you can get a small midi keyboard and bash at it using some free software, is very accessible nowadays! (Plenty of YouTube tutorials, I use reaper but plenty of other free tools to try). As far as working out goes, I lacked the motivation too, but then got a couple of dumbbells and would do some small movements while watching movies or shows at home. It's slow progress but eventually gets to the point that you enjoy it. You're already sat there watching TV, so this is just adding one small thing into that. I do feel more motivated after moving a little, so maybe that would work for you.

Find what you want from a hobby.

After trial and error for a few years, I realized I wanted my hobby to create something useful in the end. That helped me really narrow down my options.

Now, my favorite things to do include cooking (then get to eat it), crochet (then get to wear it/sell it/give it away), and playing RPGs (then get to beat it, etc.).

Hope this helps!

I know music has already been stated, but learning an instrument during my episodes greatly helped me. It's not super interesting at first, but if your symptoms are like mine and others, sometimes just having the boring distraction of practicing a scale pattern can be that helpful. Learning the patterns of the major scale and doing that repeatedly can just be a nice way to productively occupy your mind and hands long enough for the episodes to pass when they get bad. And once you get to a point where you passively start hearing different ways to play that scale, you begin to improvise and it can actually go from boredom to fun. Another cool trick is that if you're used to typical 12 note scale stuff and associate Major sounds with "happy" sounds, it can give your brain just a little cognitive dissonance and help jolt you out of some moods if you're in a lighter episode.

Again: it's something that has worked for me. I don't think there's anything wrong with you if it doesn't work for you. But maybe it could be worth trying if you have access to an instrument.

I’d recommend an in-person game of Pathfinder or DnD. The great thing about the game for me is getting rid of the electronics for a while and trying to be as creative as possible. If you can think it up, and convince the DM, you can do it be anything you want. Be as creative as you want. Come up with a character and their backstory and have fun.

Once you’ve played for a bit and have a good handle on things trying DMing. I was more afraid than I should have been and found that it is a ton of fun. Between getting to come up with and run the games I like to add my own twists and turns, bring things from previous sessions in as a surprise and most of all I love to see the creativity from the players and seeing how they ~~fuck up all my carefully laid plans~~ come up with amazing ideas and surprise me.

It can be an amazing outlet and a place to make some new friends. If you find a group that doesn’t work with you don’t be afraid to find a different one though, and remember that it’s meant to be fun.

What kinds of stuff are you interested in?
What do you like?

Music, art, working out, programming, biking, gardening, modding cars, woodworking, cooking... Any hobby can be a great thing for knocking out depression. You just have to be honest with yourself about things that you like, your current level of skills, what kinds of projects it makes sense to tackle on your own, and so on.

Therapy is the best hobby.

Working out

Backyard birdwatching? Collect recipes like on Pinterest that look good and if you feel like it later you'll have some good recipes to try making?

I picked up plants when I got depressed. Not only are they cool, but it is nice seeing something grow and nurtured. Plus, I learned that there isn't enough sunlight in my home which contributed to my depression.

The only thing I recommend is not to get a hard starter plant like calathea/goeppertia but like a spider plant. Really cool seeing them explode with growth!

Any kind of exercise, and social interaction. A combination is best, ie a team sports like basketball, soccer, etc. Check for local leagues, and so forth. It's a really good way to meet new friends as well.